Known trailing-edge flap systems for aerofoils of aircraft are required in order to create increased lift in specific flying situations and therefore, for example, in order to make it possible to fly more slowly. These specific flight situations are particularly the landing approach and the landing itself as well as the entire take-off process. The trailing-edge flaps, which are also referred to as landing flaps, can be extended using the known trailing-edge flap systems and both the surface of the wing as well as the curvature of the aerofoil profile are thus increased. In order to prevent a stall at the aerofoil during this increase, a defined opening or ‘gap’ between the aerofoil and the trailing edge as well as a projection or ‘overlap’ of the aerofoil over the trailing-edge flap are required from an aerodynamic point of view. The term ‘trailing edge’ refers to the arrangement of the flap, namely at the rear edge of the respective aerofoil in the direction of flight.
For example known trailing-edge flaps use rail systems for the movement of the trailing-edge flaps, on which rail systems the trailing-edge flaps can be moved in a guided manner. A drawback of these rails is their constructional shape beneath the aerofoil and their subsequent influence on the aerodynamics. In particular their flow resistance is disadvantageous with regard to flight stability and fuel consumption. Furthermore, the known trailing-edge flaps cannot be adapted completely to the aerofoils, so aerodynamic integration into the aerofoil contour is not possible. Instead, fairings are necessary, which also pose the drawback of increased flow resistance.
A trailing-edge flap system is known from DE 103 28 540 that is constructed without a rail system. A telescope drive is used for movement of the trailing-edge flap. A lever system is used for rotation of the trailing-edge flap and utilises the relative movement between two telescopic boxes for rotation of the trailing-edge flap. However, a drawback of a system of this type is the hindered design with regard to known design criteria. The design of a trailing-edge flap is defined over three positions. These are based on three flight situations. The ‘0°’ position is thus provided for cruising, in which the trailing-edge flap is retracted and not rotated. The two other design positions are found in the extended state of the trailing-edge flap. Within the scope of this application, the 10° and 40° positions are used purely in an exemplary manner. Of course, other positions in the extended state are also possible as design positions. The ‘10°’ position is provided as an example of the take-off process, in which position the trailing-edge flap is extended over a defined gap and a defined overlap, and includes a rotation of 10°. The ‘40°’ position is provided as an example of the landing process in this application, in which position the trailing-edge flap is extended over a defined ‘gap’ and a defined ‘overlap’, further than in the 10° position, and includes a rotation of 40°. The problem of the embodiment of a system according to DE 103 28 540 is the fact that only linear movements are possible using the telescope drive, but the pivot for the three design positions (in this instance at 0°, 10° and 40°), do not necessarily lie on a straight line. The design of this known system cannot thus be realised, or can only be realised in a defective manner, which virtually blocks the market for development of a system to be permitted for air service. The system known from DE 103 28 540 is also disadvantageous since the trailing-edge flap is rotationally mounted via the lever kinematics of the rotational movement. This arrangement is disadvantageous with regard to the air loads that occur during flight operations since relatively large levers transfer the force of the air load and the bearings of the lever kinematics must be configured so as to be correspondingly strong.